The fields of application of the device of the invention are many, and in particular include odontology, stomatology, orthodontics and plastic and reparative surgery on the human face.
The device of the invention is more particularly designed to facilitate operations for dental and periodontal reconstruction and repair, in accordance with the aesthetic harmony of the face of a subject, as well as operations for aesthetic surgery in the oral field, for re-establishing the aesthetic harmony of the face.
It is considered traditionally, from the medical viewpoint, that a face exhibits a harmonious appearance when a set of criteria, and in particular parallelism, perpendicularity and symmetry are observed.
These criteria particularly concern five individual lines of the face, namely:                the bi-pupillary line, meaning the line passing through the two pupils of the eyes of the subject,        the ophriatic line, meaning the line passing through the top edges of the two eyebrows of the subject,        the bicommissural line, meaning the line passing through the commissures of the lips of the subject,        the line of the free edges of the teeth of the anterior maxillary or the incisive line, or as known in popular terminology, “the smile line” and        the line of the anterior maxillary gum contours.        
These five lines are completed by the Camper's plane, a plane defined by the two lines joining the sub-nasal points and the porions (or the tragi) on each side, or similarly by the horizontal and the line passing through the sub-nasal point and the porions. The ideal occlusion plane falls in a plane parallel to this Camper's plane.
These five lines must also be perpendicular to the median sagittal plane of the face of the subject, on which ideally the point of the nose, the philtrum and the inter-incisive line all lie.
Although these rules are accepted collectively, the measurements are currently performed in a manner that is approximate and subjective by the practitioners concerned, who base their assessment either on their visual impression or on random measuring methods and freehand, for lack of tools for materialization and objective measurement of the various aesthetic criteria mentioned above.
However the precise location of these aesthetic parameters is essential in order to determine and quantify the asymmetries of the face and/or of the jaw of each patient, to measure these asymmetries, and thus to determine the profiles, dimensioning and orientation of operations for reconstruction to be performed in order to restore the aesthetic harmony of the face of the patient, and in particular the creation of maxillary and/or mandibular dental prostheses, as well as their periodontal integration.
In the area of dental reconstruction, verification and observance of parallelism of the ideal incisive line with the bi-pupillary line and of the perpendicularity of this said ideal incisive line with the median sagittal plane, as well as verification of the symmetry of the dental implantation of the patients in relation to this median sagittal plane, are essential for obtaining aesthetic harmony.
The principal difficulty at present for practitioners in the context of dental and periodontal restoration treatments concerns simultaneous observance of the functional occlusion criteria and the criteria governing the aesthetic harmony of the face.
Observance of these aesthetic criteria cannot however follow directly from observance of the functional occlusion anatomical criteria of the patients treated, since these functional criteria are today mastered and determinable by practitioners by means of tools such as facial arcs and articulators.
Facial arcs are used to record the spatial position of the upper maxillary of the patient in relation to a reference plane known as the Frankfurt plane and then its transfer to the articulators for the creation of complete or partial maxillary prostheses and adjustment of the dental occlusion in harmony with the particular physiology of the patient before implantation in the patients.
These facial arcs, of which documents EP 1 600 117 A, U.S. Pat. No. 6,109,917 and U.S. Pat. No. 7,048,539 B2 give miscellaneous examples, do not allow location of the aesthetic parameters of the face. Neither do they allow diagnosis of dental asymmetries in relation to these aesthetic parameters.
Moreover, since the facial arcs make use of the soft and mobile parts of the face, they do not allow reliable and reproducible recording of the maxillary position. In addition it is very common to observe an asymmetry between firstly the functional reference planes and axes and secondly the bi-pupillary line which is the aesthetic reference, unavoidably falsifying the location of the aesthetic parameters.
We do not know at present of a reliable tool to establish, in a precise and reproducible manner, the location and the measurements of the aesthetic parameters of the face. These measurements are effected in an approximate and subjective manner by the practitioners, who base their assessment either on their visual impression, or on random measuring methods and freehand, for lack of an objective measuring tool.